Go/GoLang check IP address in range

IP addresses are represented as bigendian []byte slices in go (the IP type) so will compare correctly using bytes.Compare.

Eg (play)

package main

import (
    "bytes"
    "fmt"
    "net"
)

var (
    ip1 = net.ParseIP("216.14.49.184")
    ip2 = net.ParseIP("216.14.49.191")
)

func check(ip string) bool {
    trial := net.ParseIP(ip)
    if trial.To4() == nil {
        fmt.Printf("%v is not an IPv4 address\n", trial)
        return false
    }
    if bytes.Compare(trial, ip1) >= 0 && bytes.Compare(trial, ip2) <= 0 {
        fmt.Printf("%v is between %v and %v\n", trial, ip1, ip2)
        return true
    }
    fmt.Printf("%v is NOT between %v and %v\n", trial, ip1, ip2)
    return false
}

func main() {
    check("1.2.3.4")
    check("216.14.49.185")
    check("1::16")
}

Which produces

1.2.3.4 is NOT between 216.14.49.184 and 216.14.49.191
216.14.49.185 is between 216.14.49.184 and 216.14.49.191
1::16 is not an IPv4 address

Leave a Comment

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)